I wouldn't be surprised if Square Enix made FFXVI a 3DS game. From a business perspective it may actually be a wise move. Development of FFXIV was rocky, and they had to make a whole new game. FFXV has also had a turbulent development and a platform change. Costly stuff!
How to re cooperate those losses and cut development times and costs? Release a game on a handheld platform with an insane user base. It wouldn't be the first time SE have experimented with something like this, as Dragon Quest IX was released for DS.
Could FFXVI follow suit and, if so, how would you feel about the decision?